Recurrent pericarditis: still idiopathic? The pros and cons of a well-honoured term.

In developed countries, more than 80% of cases of acute pericarditis remain without an established diagnosis after a conventional and standard diagnostic approach. These cases are generally labelled as 'idiopathic', i.e. without a known cause. This lack of information is a matter of concern for both patients and clinicians. Some years ago, this term reflected the state of the art of scientific knowledge on the topic. Advances have changed this point of view, in light of available molecular techniques like polymerase chain reaction able to identify viral cardiotropic agents in pericardial fluid and biopsies. Furthermore, the remarkable efficacy of interleukin-1 antagonists, a therapy targeting the innate immune response, suggests clinical and pathogenic similarity between a proportion of patients with idiopathic recurrent pericarditis and classical autoinflammatory diseases. So, it seems useful to discuss the pros and cons of using the term "idiopathic" in light of the new knowledge.